gnat ogres

(Holcocephala spp.)


Holcocephala is a genus of small robber flies called gnat ogres. It occurs in North America, Central America, and South America. In the United States, it occurs east of the Great Plains. It also occurs in southern Quebec and Ontario.

There are at least 40 Holcocephala species worldwide, 3 species in North America north of Mexico, and 2 species in Minnesota.

Adults are active from June to September. They are found in meadows, fields, wetlands, and woodlands, and at the margins of streams. When foraging, they perch mostly at the tips of dead twigs but also at the tips of vegetation. They are most active in the morning.

gnat ogre (Holcocephala sp.)
Photo by Alfredo Colon

Gnat ogres are soft bodied and small, to (4.0 to 9.4 mm) in length. The head is short but very wide. The eyes are very large, and they are widely spaced, giving the insect a goggle-eyed appearance. The antennae are short, no longer than the head.

The thorax is prominent and high. It is steeply arched in front and at the rear. It is densely covered with short, velvety hairs that completely hide the underlying color. It is pale with a broad, dark, longitudinal stripe in the middle and two or three dark brown spots on each side (subdorsal).

The abdomen is short, broad at the base, and tapered toward the tip.

The wings are longer than the abdomen. They are blackish, mostly dark, pale on the outer third. They are held over the body when at rest. Every cell near the wing tip is broadly open.

The legs are long.


Distribution Map



24, 29, 30, 82, 83.



Diptera (flies)








Asilidae (robber flies)






Most sources place the genus Holcocephala in the tribe Damalini. However, a handful of sources reject that name as a junior synonym of Xenomyzini, following Article 40.1 of the ICZN rules. The name Trigonomimini is older and therefore has precedence. The short list of sources that place Holcocephala in the tribe Trigonomimini includes Robber Flies of the World, AsilidaeData, The National Museum of Natural History at the Smithsonian Institution, and iNaturalist.


Subordinate Taxa

Holcocephala abdominalis

Holcocephala affinis

Holcocephala agalla

Holcocephala analis

Holcocephala bechyneorum

Holcocephala calva

Holcocephala coriacea

Holcocephala curvicosta

Holcocephala deltoidea

Holcocephala dimidiata

Holcocephala divisa

Holcocephala fernandezi

Holcocephala fimbriata

Holcocephala fusca

Holcocephala indigena

Holcocephala inornata

Holcocephala luteipes

Holcocephala macula

Holcocephala matteii

Holcocephala minuta

Holcocephala mogiana

Holcocephala monticola

Holcocephala nigrita

Holcocephala nitida

Holcocephala nodosipes

Holcocephala obscuripennis

Holcocephala oculata

Holcocephala pardalina

Holcocephala pectinata

Holcocephala pennipes

Holcocephala peruviana

Holcocephala rufithorax

Holcocephala scopifer

Holcocephala spinipes

Holcocephala stylata

Holcocephala tijucana

Holcocephala uruguayensis

Holcocephala vallestris

Holcocephala vicina

Holcocephala vittata



Helcocephala (misspelling)

Holocephala (misspelling)


Common Names

gnat ogres












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Alfredo Colon

gnat ogre (Holcocephala sp.)   gnat ogre (Holcocephala sp.)
gnat ogre (Holcocephala sp.)  

gnat ogre (Holcocephala sp.) Photos











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Other Videos

Robber fly eating insects & grooming | Holcocephala


Aug 27, 2020

Robber fly eating insects & grooming | flying, feeding, hunting / catching prey, attack | Holcocephala fusca / abdominalis, gnat ogre | assassin, Asilidae | cleaning itself | close up | Facts, Information, Documentary, Identification, Habitat, Behavior, Habits | Diet: wasp, bee, spider, dragonfly | bite | eyes, mouthparts, mystax, stout proboscis, sharp sucking hypopharynx | HD video | Animal, Wildlife, Nature |

Gnat-Ogre Robber Fly (Holcocephala sp) cleaning
Mark Berman


Jul 25, 2019

Gnat-Ogre Robber Fly (Holcocephala sp) cleaning

(Walnut Woods Metro Park, Franklin County, Ohio, USA, 23JUL2019,

ROBBER FLY, Holcocephala feediing on beetle
Rob Curtis


Jul 4, 2020

ROBBER FLY, Holcocephala feediing on beetle. McClaughery Springs FP, IL. 9/15/2019 1305750



Visitor Sightings

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Alfredo Colon

Location: Albany, NY

gnat ogre (Holcocephala sp.)

Alfredo Colon

Location: Albany, NY

gnat ogre (Holcocephala sp.)

Alfredo Colon

Location: Albany, NY

gnat ogre (Holcocephala sp.) Sightings






Created: 5/27/2024

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